Scientists have extracted a 400-year record of El Niño events using coral reef cores drilled from the Pacific Ocean, revealing crucial new insight on how these weather patterns have changed.
And, the data so far suggest something ‘unusual’ has been happening in recent decades.
According to the new research, El Niño events appear to be cropping up more frequently in the central Pacific than they have in past centuries, and while eastern El Niños may be getting stronger.
A team of scientists from the University of New South Wales developed a method to obtain the centuries-long seasonal record using coral cores – a feat previously thought to be impossible.
Much like tree rings, coral cores hold growth patterns and isotopes that can provide information about the local environmental history.
By combining this with machine learning techniques, the team was able to piece together the record going back 400 years and compare this with the more recent data.
‘We are seeing more El Niños forming in the central Pacific Ocean in recent decades, which is unusual across the past 400 years,’ said lead author Dr Mandy Freund.
‘There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity.’
According to the researchers, the El Niño events in the last 30 years included the strongest ever recorded between both the 100-year instrumental record and the historical record obtained from the coral.
‘By understanding the past, we are better equipped to understand the future, especially in the context of climate change,’ said Dr Freund.
‘Prior to this research, we did not know how frequently different types of El Niño occurred in past centuries,’ said co-author from the Centre of Excellence for Climate Extremes Dr Ben Henley. ‘Now we do.’
The researchers say the El Niño behavior observed in the central Pacific over the last few decades is unprecedented compared to past centuries.
This new insight could now help scientists prepare for future events.
‘The El Nino phenomenon is one of the most important features of global climate, and changes to its behavior have very serious implications for weather patterns and extreme events around the world,’ Dr Henley said.
‘This gives us an opportunity to more accurately explore how global warming may change El Niños and what this means for future weather and climate extremes.
‘Having a better understanding of how different types of El Niños have affected us in the past and present, will mean we are more able to model, predict, and plan for future El Niños and their wide-ranging impacts.’